US military chiefs are investigating whether the first soldier to be killed in action in Afghanistan was a victim of "friendly fire".

It was originally believed that Army Chief Warrant Officer Stanley Harriman of North Carolina was killed in an enemy mortar attack on 2 March at the opening of the offensive against al-Qaeda fighters regrouping in the Shah-e-Kot valley.

The coincidence of the timing of the AC-130 strike and the strike on that convoy were sufficient to cause me to ask the question

General Tommy Franks

But General Tommy Franks, the field commander of the US military operation in Afghanistan, revealed he had asked for an investigation into whether Warrant Officer Harriman could have been killed by "friendly fire".

The disclosure was part of a report released by the Pentagon into 10 cases of possible "friendly fire" incidents, civilian casualties and damage to property since US troops invaded Afghanistan nearly six months ago.

The US military has acknowledged some errors while saying it was not guilty of fault in other incidents. Some cases remain under review.

Mistakes could not be prevented in war, General Franks said

General Franks said he instigated the Harriman inquiry when he learned a US AC-130 gunship had reported firing on a convoy in the same area and at the same time as Warrant Officer Harriman's group was hit.

"The coincidence of the timing of the AC-130 strike and the strike on that convoy were in my view sufficient to cause me to ask the question," he said.

'A hero'

Warrant Officer Harriman's widow, Sheila, said he died fighting for his country, whoever fired the shot that killed him.

"Regardless of how he was killed, it will never change the fact that he was over there
fighting for our freedom. He's still a hero."

The report reiterated the Pentagon's earlier assertions that there were no errors in targeting in a 23 January raid on two suspected enemy compounds in Hazar Qadam, 60 kilometes (38 miles) north of Kandahar.

US troops killed 16 people and captured 27, none of whom turned out to be members of either al-Qaeda or the Taleban. The 27 were later released.

"The fact of the matter is that this is a war," General Franks said.

"The fact is we're never going to be able to absolutely eradicate the loss of life - and in some cases the loss of the wrong life - when we are engaged in these kinds of operations," he said.

Other incidents

The report also said:

A United Nations convoy was damaged by debris from bombing in November, partly because the convoy was "not travelling on the days for which it had requested and received clearance".

Red Cross warehouses were bombed on 16 October as they were in a compound also used by the Taleban and because the Red Cross failed to include them on a list of its facilities, the report said without making a conclusion on another bombing of the site on 26 October.

An inquiry continues into a 5 December incident in which a bomb from a US warplane providing support for a ground battle killed three Americans and six Afghan allies, and injured 20 Americans and 18 Afghans.

Officials concluded force was only used to secure or subdue prisoners in two incidents in which there were allegations of mistreatment.